Invasive lobular carcinoma

Invasive lobular carcinoma, abbreviated ILC, is the second most common form of Invasive breast cancer.

Invasive lobular carcinoma
Diagnosis in short
Lobular carcinoma. H&E stain.
LM DDx	invasive ductal carcinoma of the breast with lobular features, poorly differentiated carcinoma, LCIS
IHC	E-cadherin -ve, usu. ER and PR +ve, HER2 -ve, CK7 +ve
Grossing notes	mastectomy grossing
Staging	breast cancer staging
Site	breast - see invasive breast cancer
Syndromes	hereditary diffuse gastric cancer
Prevalence	relatively common
Clin. DDx	other breast tumours

It may be referred to as lobular carcinoma; however, this may lead to confusion with lobular carcinoma in situ.

General

• May be associated with a CDH1 mutation - seen in diffuse type gastric cancer.

Microscopic

Features:

• "Single file" - cell line-up in a row.
  • Cell should not be cohesive -- lymphoma should briefly come to mind.
    • primary lymphoma of the breast exists... but it is extremely rare.
• NO gland formation.
  • If it forms glands... it is more likely NST.
• May have signet ring morphology.
• NO desmoplastic reaction, i.e. the stroma surrounding the tumour cells should look benign and undisturbed.

Note:

• Commonly have low grade nuclear features.

DDx:

• Invasive ductal carcinoma of the breast with lobular features.
• Poorly differentiated carcinoma.
• LCIS.
• Malignant melanoma.

Subclassification

• Classic lobular carcinoma.
  • Low nuclear grade - NO significant variation of nucleus size.
• Pleomorphic lobular carcinoma.
  • Significant nuclear atypia.

Note:

• Some pathologist grade lobular carcinoma like other types and avoid the term "pleomorphic lobular carcinoma."

Other variants:

• Histiocytoid.

Images

• 

  Lobular carcinoma - low mag. (WC/Nephron)

• 

  Lobular carcinoma - high mag. (WC/Nephron)

• 

  Lobular carcinoma - very high mag. (WC/Nephron)

• 

  Lobular carcinoma - 1 (WC)

• 

  Lobular carcinoma - 2 (WC)

IHC

Features:

• E-cadherin -ve.
• ER and PR +ve.
• HER2 -ve.
• CK7 +ve.

Others:

• CK20 -ve.

See also

• Invasive breast cancer.
• Signet ring cell carcinoma.